Specialist legal advice for UK employers on requesting, assigning and managing Certificates of Sponsorship, including Defined and Undefined CoS, Skilled Worker sponsorship, salary and occupation code requirements, Immigration Skills Charge and sponsor compliance.
A Certificate of Sponsorship (CoS) is a fundamental part of the UK’s sponsored work immigration system.
Before an eligible overseas worker can make a successful application under a sponsored Worker or Temporary Worker route, their licensed sponsor will generally need to assign the appropriate Certificate of Sponsorship.
Despite its name, a CoS is not a paper certificate. It is an electronic record created and assigned through the Home Office’s Sponsorship Management System (SMS). It contains a unique reference number together with important information about the worker and the employment being sponsored.
The information entered on a CoS must be accurate.
Errors involving the occupation code, salary, working hours, job duties, work location or type of CoS can affect the worker’s immigration application and may also create compliance problems for the employer.
At Knights & Shah Solicitors, we advise licensed sponsors on Certificate of Sponsorship matters, from determining which type of CoS is required to reviewing proposed roles, salary and sponsorship information before assignment.
A Certificate of Sponsorship is an electronic sponsorship record containing details of the job for which a worker is being sponsored.
Once assigned, the worker receives a unique CoS reference number which is used for their immigration application.
A CoS does not itself grant a visa or immigration permission.
The worker must still make the appropriate immigration application and satisfy the requirements of the relevant route.
The Certificate of Sponsorship connects the employer’s sponsorship responsibilities with the worker’s immigration application. Information recorded on it can therefore be central to UKVI’s assessment of whether the proposed employment satisfies the Immigration Rules.
A sponsor should never treat assignment of a CoS as a routine administrative exercise.
An organisation normally needs an appropriate Sponsor Licence before it can assign Certificates of Sponsorship.
The licence must cover the immigration route under which the organisation intends to sponsor the worker.
Certificates are managed through the Sponsorship Management System, with access controlled through authorised users appointed by the sponsor.
The organisation remains responsible for the actions carried out through its SMS account.
Before assigning a CoS, the sponsor should therefore be satisfied that:
For Skilled Worker sponsorship, understanding the distinction between Defined and Undefined Certificates of Sponsorship is particularly important.
A Defined CoS is required for a Skilled Worker who will be making their application for entry clearance from outside the UK.
Defined CoS are not provided through an annual allocation. The sponsor applies for them through the Sponsorship Management System as and when required.
The request needs to contain information about the proposed employment, including relevant job and salary details.
UKVI may examine the request before deciding whether the Defined CoS should be granted.
An Undefined CoS is used in circumstances covered by the sponsor’s annual allocation, including Skilled Workers making eligible applications for permission to stay from within the UK.
When applying for a Sponsor Licence under Skilled Worker, an organisation may be asked to estimate the number of Undefined CoS it expects to require during its first year and why.
Using the wrong type of CoS can have serious consequences. In particular, assigning an Undefined CoS where a Defined CoS is required can amount to a serious breach of sponsor duties.
A licensed sponsor requiring a Defined CoS for a Skilled Worker applies through the SMS.
The organisation should be ready to provide accurate details concerning the role it intends to sponsor.
Depending upon the circumstances, UKVI may consider:
A sponsor may apply for a Defined CoS where it has already identified the worker. Current Skilled Worker guidance also permits an application where the particular worker has not yet been identified, provided the sponsor has an eligible role and reasonably anticipates needing to sponsor someone from outside the UK.
UKVI can request further information before deciding a Defined CoS request.
The employer should therefore ensure that the request accurately reflects the genuine vacancy.
Undefined Certificates of Sponsorship operate differently.
Sponsors may receive an allocation which enables them to assign CoS for eligible circumstances during the relevant allocation period.
The number required should be considered realistically.
UKVI may expect an organisation to justify why it requires a particular number of Certificates of Sponsorship. The Home Office’s guidance requires sponsors to think carefully about the number of workers they are likely to employ and why.
Businesses should avoid treating CoS allocation requests as an opportunity to obtain an unnecessarily large reserve of sponsorship capacity.
Where additional Undefined CoS are required, the sponsor may need to request an increase through the appropriate Home Office process.
The information required depends upon the immigration route, but a Certificate of Sponsorship can contain important details about both the worker and the proposed employment.
This may include:
The information should correspond with the genuine terms of employment and other supporting records.
Discrepancies between the CoS, employment contract, payroll information, visa application or actual duties performed can attract Home Office scrutiny.
Selecting the appropriate occupation code is an important part of Skilled Worker sponsorship.
The code should reflect the actual duties of the role, rather than simply the job title the employer prefers to use.
Before assigning a CoS, the employer should consider:
An inappropriate occupation code should not be used simply because it produces a more favourable immigration outcome.
The Home Office can investigate whether the code corresponds with the job actually being performed, and inappropriate use of an occupation code can create serious compliance concerns.
Salary is another critical part of sponsorship.
The amount stated on the Certificate of Sponsorship should satisfy the requirements applicable to the particular immigration route and occupation.
The correct threshold can depend upon matters including:
The salary entered on the CoS should also correspond with the genuine employment arrangements.
Sponsors should be particularly careful where working hours, salary or the worker’s circumstances change between the initial sponsorship planning and assignment of the CoS.
A figure should never be entered simply to satisfy an immigration threshold if it does not reflect what the worker will actually receive.
A Certificate of Sponsorship should only be assigned for genuine employment.
The Home Office may examine whether the role:
UKVI can consider the organisation’s size, business activities, workforce and structure when assessing whether a vacancy is genuine.
For example, a proposed senior position may attract questions if its duties and salary appear inconsistent with the size or activities of the business.
The employer should therefore be capable of explaining why the role exists and how it fits within its operations.
Once a Certificate of Sponsorship has been assigned, the worker generally needs to use it to make their visa or permission application within three months.
The worker must also not apply more than three months before the employment start date stated on the CoS.
Timing therefore matters.
Employers should coordinate assignment with:
Assigning a CoS too early or allowing it to expire can cause unnecessary delays.
The sponsor must pay a fee when assigning a Certificate of Sponsorship.
As at August 2026, the published Home Office fee is:
Different treatment applies to International Sportsperson sponsorship depending upon the length of sponsorship.
Government fees can change, so the applicable amount should be checked when the CoS is being assigned.
For specified Worker and Temporary Worker routes, the sponsor must pay the CoS fee itself and must not pass prohibited sponsorship costs to the worker. Breach of these rules can place the Sponsor Licence at risk.
Assigning a Certificate of Sponsorship can also trigger the Immigration Skills Charge (ISC).
The charge commonly applies when sponsoring workers under routes such as Skilled Worker and Senior or Specialist Worker, subject to applicable exemptions.
The amount depends upon factors including:
As at August 2026, the published charge is £480 for the first 12 months for a small or charitable sponsor and £1,320 for a medium or large sponsor, with additional amounts for each further six months.
The Immigration Skills Charge is separate from the CoS assignment fee.
Where it applies, it is paid by the sponsor when assigning the Certificate of Sponsorship and must not be passed to the sponsored worker in circumstances prohibited by the sponsorship rules.
Errors should be dealt with carefully.
Common problems can include:
Whether an error can be corrected depends upon what has happened and the nature of the mistake.
Some limited information may be capable of clarification through a sponsor note or appropriate SMS action. More fundamental changes may require a different approach, potentially including withdrawal or assignment of a new CoS.
For Defined CoS in particular, Home Office guidance restricts the changes that can be made when the certificate is assigned. Significant changes, such as certain changes to salary, working hours, occupation code or job description, may require UKVI involvement rather than simply altering the approved request.
Employers should therefore seek advice before attempting to correct a material CoS error.
The Home Office can compare information contained in a CoS against:
Serious discrepancies can raise concerns about whether sponsorship information was accurate.
Examples can include:
The Skilled Worker sponsor guidance warns that false information concerning Defined CoS can lead to Sponsor Licence revocation.
A CoS should therefore be treated as an important compliance record, not simply a reference number needed for a visa application.
Once the CoS has been assigned, the worker can use the reference number to make the relevant immigration application.
The employer’s responsibilities do not end at assignment.
The sponsor may need to:
Changes after sponsorship begins may need to be reported to UKVI, and significant changes can sometimes require a new immigration application.
There may be circumstances where a CoS needs to be withdrawn or sponsorship needs to end.
For example, the worker may decide not to take the role, recruitment plans may change or an error may be discovered before the immigration application proceeds.
The appropriate SMS action depends upon the status of the CoS and what has already happened.
Sponsors should avoid leaving inaccurate or obsolete sponsorship records unresolved.
Where a worker has already obtained immigration permission, ending sponsorship can have immigration consequences for that worker and should be handled through the correct reporting process.
Some of the most significant problems arise from avoidable errors.
These include:
Checking the proposed sponsorship before assignment can prevent much more serious problems later.
At Knights & Shah Solicitors, we advise employers on Certificate of Sponsorship matters as part of their wider Sponsor Licence and business immigration responsibilities.
We can assist with:
Our aim is to ensure that the proposed sponsorship is considered before the Certificate is assigned, reducing the risk of avoidable errors affecting either the worker’s immigration application or the employer’s Sponsor Licence.
If you require advice contact Knights & Shah Solicitors.
We provide clear, solicitor led advice, strategic case planning and robust court representation to protect our clients.
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